RDMA/rtrs-srv: Fix stack-out-of-bounds

RDMA/rtrs-srv: Fix stack-out-of-bounds

  BUG: KASAN: stack-out-of-bounds in _mlx4_ib_post_send+0x1bd2/0x2770 [mlx4_ib]
  Read of size 4 at addr ffff8880d5a7f980 by task kworker/0:1H/565

  CPU: 0 PID: 565 Comm: kworker/0:1H Tainted: G           O      5.4.84-storage #5.4.84-1+feature+linux+5.4.y+dbg+20201216.1319+b6b887b~deb10
  Hardware name: Supermicro H8QG6/H8QG6, BIOS 3.00       09/04/2012
  Workqueue: ib-comp-wq ib_cq_poll_work [ib_core]
  Call Trace:
   dump_stack+0x96/0xe0
   print_address_description.constprop.4+0x1f/0x300
   ? irq_work_claim+0x2e/0x50
   __kasan_report.cold.8+0x78/0x92
   ? _mlx4_ib_post_send+0x1bd2/0x2770 [mlx4_ib]
   kasan_report+0x10/0x20
   _mlx4_ib_post_send+0x1bd2/0x2770 [mlx4_ib]
   ? check_chain_key+0x1d7/0x2e0
   ? _mlx4_ib_post_recv+0x630/0x630 [mlx4_ib]
   ? lockdep_hardirqs_on+0x1a8/0x290
   ? stack_depot_save+0x218/0x56e
   ? do_profile_hits.isra.6.cold.13+0x1d/0x1d
   ? check_chain_key+0x1d7/0x2e0
   ? save_stack+0x4d/0x80
   ? save_stack+0x19/0x80
   ? __kasan_slab_free+0x125/0x170
   ? kfree+0xe7/0x3b0
   rdma_write_sg+0x5b0/0x950 [rtrs_server]

The problem is when we send imm_wr, the type should be ib_rdma_wr, so hw
driver like mlx4 can do rdma_wr(wr), so fix it by use the ib_rdma_wr as
type for imm_wr.

Fixes: 9cb837480424 ("RDMA/rtrs: server: main functionality")
Link: https://lore.kernel.org/r/20210212134525.103456-2-jinpu.wang@cloud.ionos.com
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Gioh Kim <gi-oh.kim@cloud.ionos.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>